Add a shortcut that opens Certificate Viewer from the Page Info flyout

Add a shortcut that opens Certificate Viewer from the Page Info flyout

In M56 (crbug.com/646465) we changed replaced the "Details" link on the
Page Info flyout with a "Learn More" link that opens the Help Center.
The old "Details" link opened the Developer Tools Security Panel (or
launched the Certificate Viewer directly in the event that the
Developer Tools were disabled by policy).

Advanced users disliked this change as it made it significantly more
cumbersome to examine the website's certificate.

This change adds a shortcut to open the Certificate Viewer. Now if
the SHIFT key is down when the "Learn More" link is activated, the
Certificate Viewer will open directly.

BUG=663971

[elawrence, 2017-02-02 16:47:48]

The CQ bit was checked by elawrence@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-02-02 16:48:15]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-02 17:08:24]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-02 17:08:25]

Dry run: Try jobs failed on following builders:
  mac_chromium_compile_dbg_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)

[elawrence, 2017-02-02 17:45:54]

The CQ bit was checked by elawrence@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-02-02 17:46:23]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-02 18:38:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-02 18:38:28]

Dry run: This issue passed the CQ dry run.

[palmer, 2017-02-09 20:41:29]

palmer@chromium.org changed reviewers:
+ palmer@chromium.org

[palmer, 2017-02-09 20:41:30]

lgtm